Heat the oil in a wide-based pan over medium heat.
Add the cumin seeds, onions, and pepper flakes, and saute for a minute.
Stir in all the remaining ingredients, except the tomato paste and vinegar.
Reduce the heat, cover, and cook for about 10 minutes or until the vegetables are just tender.
Stir in the tomato paste and vinegar, mix well, and cook for 2 minutes longer.
Remove from the heat and transfer to a serving dish.
Serve hot with any meat dish, aloo soya tikki, or balti paneer, along with chapati or paratha.